1. Field of the Invention
The present invention relates to an apparatus for handling codes, a method for controlling the apparatus, and a program.
2. Description of the Related Art
When electronic data is printed on a paper medium, it is difficult to ensure security for the paper medium. The level of security for such a paper medium may currently be low.
To overcome the above issue, techniques for providing tracking information to specify where information may have leaked have been proposed as a measure for increasing the level of security for a paper medium on which a copy has been made. One of the techniques is to record history information onto a medium, such as paper, by adding a code (e.g., a two-dimensional code or digital watermark) to the paper medium to track information and find where information may have leaked. However, there is a limit to the amount of information that may be contained in such a code. This requires that only the most necessary information be selected for the code. As discussed in Japanese Patent Application Laid-Open No. 2008-131522, the most necessary pieces of information are selected to be included in a code. Specifically, two pieces of information are selected: the most recent information and the second most recent information. Additionally, the oldest information is deleted.
Japanese Patent Application Laid-Open No. 2008-131522 discusses a technique of adopting digital watermarking, thereby recording, on a paper medium, data about a person who owns a paper medium and data about a person who makes a copy of the paper medium.
In this technique, when a paper medium is copied to make a first copy thereof, data about a person who owns the paper medium is updated to data about a person who makes the first copy, and data about a person who makes a second copy is updated to a person who makes the second copy.
Referring to FIG. 4, the technique discussed in Japanese Patent Application Laid-Open No. 2008-131522 will now be described. When a user X makes a copy of a digitally watermarked document, the user X's name is recorded on the digitally watermarked document as owner data and as person-making-copy data. Next, if a user Y makes a copy of the digitally watermarked document as copied, the person-making-copy data of this document is updated to Y.
If a user Z makes a copy of the digitally watermarked document as copied twice, the owner data and the person-making-copy data of such a document are updated to Y and Z, respectively.
However, although the histories of the owner data and person-making-copy data recorded on a paper medium are updated each time a copy is made from a past copy on a paper medium, the trail leading to the user who produced the first print or copy from the document may be broken if one paper medium (with a copy on it) between the first one and the last one is lost. It may be difficult to, for example, specify a user who instructed an image forming apparatus to produce a print from electronic data (i.e., a user who made a copy on a paper medium).
This may make it difficult for a user who produced a print or copy to become aware of an information leak.